Single Pt Atoms Supported on Oxidized Graphene as a Promising Catalyst for Hydrolysis of Ammonia Borane

Based on density functional theory calculations, the full hydrolysis of per N\rmH_\rm3B\rmH_\rm3 molecule to produce three hydrogen molecules on single Pt atoms supported on oxidized graphene (P\rmt_1/Gr-O) is investigated. It is suggested that the first hydrogen molecule is produced by the combination of two hydrogen atoms from two successive B-H bonds breaking. Then one \rmH_\rm2O molecule attacks the left ^*BHN\rmH_\rm3 group (^* represents adsorbed state) to form ^*BH(\rmH_\rm2O)N\rmH_\rm3 and the elongated O-H bond is easily broken to produce ^*BH(OH)N\rmH_\rm3. The second \rmH_\rm2O molecule attacks ^*BH(OH)N\rmH_\rm3 to form ^*BH(OH)(\rmH_\rm2O)N\rmH_\rm3 and the breaking of O-H bond pointing to the plane of P\rmt_1/Gr-O results in the desorption of BH\rm(OH)_\rm2N\rmH_\rm3. The second hydrogen molecule is produced from two hydrogen atoms coming from two \rmH_\rm2O molecules and P\rmt_1/Gr-O is recovered after the releasing of hydrogen molecule. The third hydrogen molecule is generated by the further hydrolysis of BH\rm(OH)_\rm2N\rmH_\rm3 in water solution. The rate-limiting step of the whole process is the combination of one \rmH_\rm2O molecule and ^*BHN\rmH_\rm3 with an energy barrier of 16.1 kcal/mol. Thus, P\rmt_1/Gr-O is suggested to be a promising catalyst for hydrolysis of N\rmH_\rm3B\rmH_\rm3 at room temperature.